1. Field of the Invention
This invention relates to a method for harvesting fruits, berries and the like, in particular for gathering grapes in whole bunches. The method consists in shaking a plant bearing said fruits, berries and the like by means of shaker members which encompass the plant and are reciprocated between two end positions on each side of a mean position.
2. Description of the Prior Art
Harvesting machines equipped with shaker members driven in transverse reciprocating motion with respect to the direction of forward travel of the machine are now well-known (see for instance U.S. Pat. Nos. 3,667,202, 3,939,629, 4,198,801, 4,236,371, 4,286,426 and 4,391,085 and French Pat. Nos. 2,293,132, 2,509,955 and 2,516,742, although some of the machines disclosed in these patents use beater members instead of shaker members). In known machines of this type, the shaker members usually produce action on the plant within the fruit-bearing zone amidst the vegetation and subject the plant to a sinusoidal or pseudo-sinusoidal movement, the frequency and amplitude of which have the calculated effect of detaching the fruits. As a general rule, the movement is sinusoidal at the level of the drive mechanisms associated with the shaker members and pseudo-sinusoidal at the level of the plant by reason of the flexibility of the latter and also, in certain cases, by reason of the flexibility of the shaker members themselves. In all cases, this movement does not have any discontinuity either during shaking of a plant or during displacement of the machine from one plant to the next. The amplitude of motion (without taking into account the flexibility of the shaker members) is usually of the order of 100 mm (between 75 and 150 mm) and the shaking frequency is usually of the order of 8 cycles per second (between 6 and 10 cycles per second).
Although integral mechanical vintage or grape-harvesting is at present developing throughout the world for obvious economic reasons, a few technical difficulties still remain and tend to check its extension. In particular, the known grape-harvesting machines which are equipped with shaker members displaced in transverse reciprocating motion with respect to the direction of forward travel of the machine are attended by two disadvantages. In the first place, this mechanical action has the effect of bursting-open a relatively large number of individual grapes (called grape berries). In the second place, it has the effect of harvesting grape berries which have been detached from the bunches. These two phenomena give rise to a loss of juice, to difficulties in cleaning of the grapes owing to the number of vine leaves and to wetting of the leaves which are detached at the same time as the grapes. Further consequences include oenological problems which arise from the intimate contact of the released juice with the air and with foreign substances unrelated to the vintage, as well as vinification difficulties in certain particular cases (carbon dioxide maceration, fractional pressing). Furthermore, the shaker members tend to damage the plant itself and this is in turn liable to affect its health. As a mattter of fact, they have a tendency to produce leaf-stripping, breaking of vine-shoots which lead to difficulties in pruning, bud removal which is liable to have an adverse effect on the future yield of the plant, and injuries to the wood through which diseases may thus more readily gain entrance to the plant.
Observations made by the present Applicants by means of time-lapse cameras have in fact shown that detachment of grapes takes place after the plant has been shaked for a certain time, while giving rise to fatigue of the stems or other connecting organs which connect each "mass" (grape berries, bunches, foliage) to the remainder of the plant. Thus any failure of these connecting organs essentially takes place as a result of fatigue. During the period of time required for detachment of grapes, the bunches attached to small branches or flexible vine-shoots rotate in a random movement about their point of atttachment and the different berries of any one bunch or cluster bump against each other. The energy stored by these impacts finally causes detachment of the berries from the bunches. In consequence, when using the known machines equipped with shaker members which are driven in a sinusoidal or pseudo-sinusoidal movement, approximately 80% of the harvest consists of grape berries which have become detached from the bunches and only about 20% of the harvest consists of whole bunches. As they are detached from the bunches, the individual grape berries release juice as a result of opening of their skins. In addition, the powerful action of the shaker members in the fruit-bearing zone of the vine causes impacts between certain bunches and the shaker members. The grape berries thus burst open as a result of crushing and a substantial quantity of juice is released. Furthermore, the same powerful action of the shaker members in a portion of the plant foliage and branches produces a number of injuries including stripped or lacerated leaves, breakage of wood, removal of or injuries to shoots and buds as well as injuries to the wood.
In short, shaking of grapevines by means of shaker members driven in sinusoidal or pseudo-sinusoidal motion essentially results in detachment of grapes in the form of individual berries much more than in the form of whole bunches or clusters, releases large quantities of juice (impact upon grape clusters, detachment of grape berries) and injures the plant as a result of shock impacts on foliage and branches. The foregoing observations are also valid when these machines are employed for harvesting other fruits or berries such as, for example, red currants, black currants, gooseberries and, to some extent, raspberries.